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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9371d048c1b0e57ba6fb5418164dd22419c50b50ac1b8bc4b7eefcd1bf56ae03' 
  AND token = 'K4LOLBnvqFwnhMD5VbBeHyyiSRMsOa7nA+M/+TLoH/E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}